Acoustic diaphragm



w. A. SCHEUCH 1,759,632

ACOUSTIC DIAPHRAGM Filed July 6, 1925 May 20, 1930.

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Patented May 20, 1930 UNITED STATES PATENT OFFICE WILLIAM A. SCHEUCH, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COM- lA'NY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0F NEW YORK ACOUSTIC DIAPHRAGM lpplzoation led J'uly 6,

A ieu comprises an acoustic diau c light alloys o y for such apparatus as phonograpln producers transmitters, microphones and loud speakers. lt has been round. 'that beryllium .alleys having a high beryllium content are suihciently malleable that they may be rolled to a thinness suitable for dia- :Zc phragms and when rolled to such a thinness have a high ratio of stillness to mass which makes a diaphragm or" this material an ei'- lcient translator of high frequencies Without sacrilicing eiiiciency at low frequencies. Since 2a the material is substantially non-corrosive it may be used Without the usual protective coating which increases the diaphragm mass.

For the purpose o more clearly illustrating the invention, several applications of the use or the diaphragm are shown in the accome panying drawings of which Fig.. l is the front view of an acoustic phonograph reproducer;

Fig., 2 is a cross section taken along the c vertical central line of Fig. l; and

ig. 3 is a view or a telephone transmitter. Referring particularly to Figs. l and 2 in which like reference characters designate like parts, l indicates the phonograph rc producer housing which is mounted on the tone arm 2. Mounted near the lovver edge of housing l is a transverse support 3 upon which the stylus lever 4 pivots, the upper end olf the stylus lever contacting at the geometrical center of the acoustic diaphragm 5 upon which is mounted the spider 6. The stylus needle 7 is seated in a socket on the lower end of stylus lever 4. by means of thumb screw 8. Diaphragm 5 is suspended at its periphery by the soft rubber rings 9.

1925. Serial No. 41,479.,

Referring now to Fig. 8 wherein the diaphragm or the invention is represented as employed in a telephone 'transmitter or microphone, l() designates the casing of the receiver in which is mounted the face plate 'll which carries a mouth piece l2 and 'frame i3 lor mounting the transmitter button lil which has a contact member projiectinf therefrom into a recess in 'he center ci. ohragm 16. il. cantilever spring i7 keeps 'ie contact member l5 bn immediate contact :n accordance with on the diaphragm ne i venticns diaphragme and l@ are iormed or alloy beryllium with aluminum or magnesium or `both aluminum magnesium, which alloy 'of alloys produces diaphragms Which are particularly satisfactory as regards lightness and strength. Because oi its extreme lightness and its consequent low inertia a diaphragm of these alloys responds more readily lto minute vibrations of rapidly varying intensities than a diaphragm similar in size made of other materials. Il greater' response at high reouencies with some improvement in response at the low frequencies, because or" the reduced diaphragm impedance, is obtained :tor a given energy input, that is, a greater and more uniform response is obtained over the Whole i'requency range.

The qualities desirable for such diaphragms are found to exist to a high degree in those alloys or" beryllium with aluminum or magnesium or both aluminum and magnesium in which the beryllium comprises preferably at least 85% or the alloy. 'The proportions or" aluminum and magnesium employed will depend upon the particular use to which the alloy is applied, alloys of lighter speciiic gravity but of substantially the same strength being produced by the substitution of magnesium for aluminum. The range of alloys of ber llium With aluminum or magnesium or bot have been found to ossess properties which are more valuable or many purposes, than those of the individual metals. They have, for instance, been found to possess high tensile strength, and high permanence and uniformity of crystal structure, coupled lwith a satisfactorily low counteract them. It is not the intention however to claim a quantitative addition of manganese as it is a simpleA eXpedient'and well known to the art. y

Such alloys have greater strength than any of the individual constituent metals and are not appreciably heavier than any of them.

as to have a melting point at least as high as 1200 C.

9. An acoustic diaphragm formed of an alloy of beryllium with aluminum and magnesium in such proportions as to have a melting pointl at least as high as 1200o C.

10. An acoustic diaphragm formed of an alloy composed of -a large percentage of beryllium and smaller percentages of aluminum and magnesium.

11. An acoustic diaphragm formed of an alloy composed of the following metals in substantially the following proportions by -\weight:y beryllium 85% and the remainder aluminum and magnesium.

In :witness whereof I hereunto subscribe my name this third day of July, A. D. 1925.

WILLIAM A. SCI-IEUCH.

They have a low elastic modulus; are permanent in water, either boiling or cold; are particularly ductile and vmalleable within certain limits take and retain a high polish; resist atmospheric corrosion and have the necessary quality of impedance and crystal structure for acoustic diaphragms.

While this speciiication has reference to alloys of beryllium to be used for acoustic diaphragrns, it is to be understood that itis not intended to limit the invention to specific percentages of metals or other particular uses set forth but that any changes may be made without departing from the spirit of the ,invention Within the scope of the appended claims.

What is claimed is:

1. An acoustic diaphragm formed of an alloy comprising beryllium as its principal ingredient.

v 2. An acoustic diaphragm formed of an alloy comprising as essential elements thereof a large percentage of beryllium and a smaller percentage of aluminum.

3. An acoustic diaphragm 'formed of an alloy comprising as essential elements thereof a large percentage of beryllium and smaller percentages of aluminum and magnesium.

4. An acoustic diaphragm formed of an alloy containing as the principal ingredient an amount of beryllium at least as large as 85%.

5. An acoustic diaphragm formed of an alloy comprising as essential elements thereof, beryllium and aluminum.

6. An acoustic diaphragm formed of an alloy composed of beryllium, aluminum and magnesium.

7. An acoustic diaphragm composed of an alloy comprising as essential elements thereof an amount of beryllium, at least as great as 85% and aluminum and magnesium.

8. An acoustic diaphragm made of an alloyv comprising as essential elements thereof, aluminum and beryllium in such proportions 

